<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>背景的样式设置</title>
    <style type="text/css">
        div {
            width: 400px;
            height: 125px;
            line-height: 1.5em;
            font-size: 40px;
        }
        .bgcolor-gray {
            color: white;
            background-color: gray;
        }
    </style>
</head>
<body>
    <div class="bgcolor-gray">该段落背景色为灰色</div>
</body>
</html>